March 6, 2015 by Canadian Underwriter
A new web-based computer tool shows about 21 million people a year could be affected by river flooding and 15 nations have more than 1% of their annual gross domestic product exposed to such flooding, though a Munich Reinsurance Company climate research executive suggests that losses can be mitigated through better flood control and zoning.
Aqueduct Global Flood Analyzer is a web tool designed to measure the effects of river flooding.
The software “shows that approximately 21 million people worldwide could be affected by river floods on average each year,” wrote researchers Hessel Winsemius and Philip Ward in a blog posted to the website of World Resources Institute, which co-developed the tool. “That number could increase to 54 million in 2030 due to climate change and socio-economic development.”
WRI’s co-developers were four Dutch organizations: Institute for Environmental Studies of the VU University Amsterdam; Utrecht University; PBL Netherlands Environmental Assessment Agency and Deltares, an applied research institute based in Delft.
Winsemius is a researcher for Deltares – whose research areas includes water, subsurface and infrastructure – and Ward is a senior researcher at the Institute for Environmental Studies of the VU University Amsterdam.
Commenting on their blog post, Munich Re’s Peter Höppe notes that better flood control can prevent losses.
“Particularly with floods, an increased hazard – such as more frequent heavy rainfall events – need not necessarily result in higher losses,” said Höppe, head of Munich Re Geo Risks Research and Climate Centre, in a statement. “Such a rise in losses can be prevented by better flood control. It is therefore important to sharpen risk awareness. Appropriate flood control measures can help flood waves to disperse without causing serious damage. And the flood risk needs to be considered in the designation of land for industrial or residential areas.”
On its website, WRI notes that Aqueduct Global Flood Analyzer “measures river flood impacts by urban damage, affected GDP, and affected population at the country, state, and river basin scale across the globe.” The tool “aims to raise the awareness about flood risks and climate change impacts by providing open access to global flood risk data free of charge.”
The tool provides estimates of “current and future potential exposed GDP, affected population and urban damage from river floods for every state, country and major river basin in the world.”
At the WRI website, users can search by country, basin or state. The tool lets users view estimates of GDP and people affected using different flood protect protection levels (for example, 500-year, 100-year or 10-year).
In Canada, for example, the GDP affected at the 25-year protection level is US$2.1 billion, while the GDP affected at the 250-year protection level is US$245.3 million. Those estimates are for 2010 but it also gives estimates for 2030 based on different scenarios.
In their blog post, Ward and Winsemius included a chart depicting the 15 countries with the greatest number of people exposed to flood river risk. The top three are India (4.84 million), Bangladesh (3.48 million) and China (3.28 million). All of the top 15 are in Asia and Africa except Brazil, which has an estimated 270,000 exposed.
It also lists the top 20 countries, ranked by highest percentage of total GDP affected by river flooding each year.
The top five were Bangladesh (4.75%), Cambodia (3.42%), Afghanistan (2.58%), Vietnam (2.29%) and Laos (2.22%). Of those, two (Bangladesh, with US$5.47 billion) and Vietnam (with $2.65 billion) had absolute values of GDP exposed annually to river flooding of greater than US$1 billion. India (with $14.317 billion) was the country on the top 20 list with the highest absolute value of GDP exposed to river flooding, though it ranked 20th (at 0.84%) in percentage.
Other countries with more than $1 billion of GDP exposed to flooding include Egypt (with US$2.557 billion, or 1.18% of its annual GDP) and Pakistan (which had $1.732 billion, or 0.98% of its annual GDP) exposed. A total of 15 countries had more than 1% of their annual GDP exposed.
The United States did not make either list, but Höppe notes the U.S. has invested about US$14 billion in flood control measures in the Mississippi region since 1927.
“Over the past 80 years, numerous dams, locks and dykes co
vering thousands of miles have been built or strengthened,” Hoppe wrote in a statement, adding that a flood in 2011 was estimated to have resulted in costs of about US$3 billion.
“However, the U.S. Army Corps of Engineers estimated that without the prior work, losses from the 2011 flood could have amounted to as much as US$237 billion,” Höppe added. “Nevertheless, the possibility that flood control measures may actually cause a rise in values in a protected region and therefore an even higher exposure there must be considered in the evaluation of future loss potentials.”
[click image below to launch the Aqueduct Global Flood Analyzer interactive tool in new window]